Lightning & Swimming Pools

I recently moved from CT to NC and have noticed one of the differences between the two areas is the amount of thunderstorms. Typically they're in the afternoon so if you tend to swim during that time your workouts are either cancelled or cut short. The safety rules which require you to get out of the pool are true for both indoor and outdoor pools (I've overheard people question the guards why it applies to indoor pools and it got me to thinking). I'm assuming the electricity would conducted through pipes or metal in the building. Does the presence of windows make a difference? Also, the frequency of storms is such that I would think it would have a fairly big impact on the ability of teams to have consistent workouts. I remember coaches who would give people a hard time about getting out for 2 minutes to use the restroom, that seems to pale in comparison to missing huge sections of workouts several days a week due to thunderstorms. The rule seems to be that if there's a lightning strike you must leave the pool and wait 20-30 minutes before re-entering the pool. Where did the 20-30 minute time frame come from? One last hypothetical question, what if during the Olympic 1500m race there's a lightning strike? Do they tell the swimmers to stop and get out?